Ignition circuit



March 13, 1962 A. R. LEPPALA 3,025,430

IGNITION CIRCUIT Filed April 8, 1959 INVENTOR. AXEL A. LEPPAL ATTORNEY 3,925,430 Patented Mar. 13, 1 962 3,025,430 IGNITION cmcurr Axel R. Lcppala, 247 W. Farihault, Duluth, Minn. Filed Apr. 8, 1959, 5er. No. 804,986 3 Claims. (Cl. 315-227) This invention relates in general to ignition systems; in particular it concerns an improved ignition circuit for use in internal combustion engines of the spark ignition or otto cycle type.

Most automobiles and a large percentage of trucks, busses, airplanes and motor boats, as well as a considerable number of stationary power plants and prime movers, use spark ignition engines. It is well known that engine manufacturers constantly tend to upgrade the performance characteristics of their products, resulting almost annually in increased horsepower, motor speeds, compression ratios and efficiencies. This pattern of improvement is generally accompanied by liberal additions in the number of power accessories normally found in automobiles and the like.

The result is to seriously tax the electrical system of the average automobile engine and to require larger amounts of electrical energy both at the ignition end of the system and for the requirements of the electrically driven accessories continuously being introduced. To this end the majority of American cars and practically all of the European cars now use 12 volt electrical systems to answer the needs of present day requirements.

However, in spite of the developments made in the direction of higher capacity electrical systems, little if any attention has been given to the problem of reducing the effect of the increased energy upon certain vital engine components. Among those components directly affected by higher voltage levels is the breaker contacts or points in the ignition system. Ordinary efforts designed to minimize burning, pitting or similar deterioration of the breaker points have included such means as shunting a condenser across the points to suppress the are when the contacts open. A resistance having a high temperature coefficient is sometimes placed in series with the primary to prevent overheating of the points when they are closed and the ignition switch happens to be inadvertently left closed. These strategems, while adequate for engines having low potential electrical systems are simply not suitable for modern engines as experience has shown that the breaker points in the newer cars need replacement much oftener than before.

Accordingly, it is a broad object of the present invention to provide an improved ignition system adapted for use in engines having high performance characteristics.

It is another object of this invention to provide in an ignition system of a spark ignition engine a novel means for prolonging the life of the distributer breaker points.

Another object of this invention is to provide a novel and improved electrical circuit designed to prevent arcing between the breaker points of an ignition system.

A further object of this invention is to provide an easily manufactured low cost accessory for reducing breaker point deterioration,

A still further object of this invention is to provide a device easily connectable between the coil and the distributer of a 4 cycle engine whereby burning and oxidation of the breaker points may be prevented.

Another object of this invention is to provide facile means for preventing high voltage peaks in the primary circuit of an ignition system.

Another object of this invention is to provide an improved ignition system adapted to facilitate cold weather starting without excessive break point deterioration. As

the temperature drops the resistance of the primary cir cuit is lowered causing more current to flow through the points which causes burning of the points. To meet this I provide a greater capacity with a condenser and choke coil. Some present day systems add a resistance but such reduces the sparks and is inadequate.

A further object of this invention is to provide added capacity to an ignition system without imposing extra wear upon the breaker points.

These and other objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawing in which is shown a representation of the invention by way of illustration only.

In the drawing:

The FIGURE is a circuit diagram showing the invention added to a conventional ignition system.

Referring now to the circuit shown in the FIGURE of the drawing wherein a typical ignition system of an automobile engine is shown, the features of my invention are enclosed within the dotted outline of the circuit.

The primary winding 17 of coil 16 is connected across battery 14 in series with the interrupter or breaker point contacts 12. The ignition coil 16 consists of a primary winding 17 of relatively few turns and a secondary winding 19 with a comparatively large number of turns, both wound over a laminated iron core 15. Contacts 12 in the interrupter are closed and opened by a rotating cam (not shown), the number of lobes of the cam corresponding to the number of cylinders. The contacts 12 are closed for a time which is sufficient to permit the flux in the core 15 of the ignition coil 16 to build up to a substantial value. Contacts 12 then open suddenly. This induces a high in the secondary 19 which causes the ignition spark to jump across the points 18 of the spark plug. The energy which is stored relatively slowly in the magnetic field is thus suddenly released and appears as heat energy between the points 18 of the spark plug. Condenser ltl shunted across contacts 12 serve to some extent to suppress the are when contacts 12 are open. However, it is known that some of the energy stored in the magnetic field of the core, especially in recently developed high performance engines, flows back through the primary side of the system causing contacts 12 to burn or otherwise suffer a diminution of their efliciency through corrosion, oxidation or pitting.

To alleviate this condition, I provide, firstly, a by pass condenser 32 connected between contacts 12 and primary winding 17 of coil 16 and grounded as at 44. Condenser 32 serves to provide added capacity for the system without affecting the condition of the contacts 12. Then I introduce into the circuit a low resistance inductance coil 30 between the conventional condenser 10 and my added condenser 32.

Coil 30 which may be referred to as a choke coil is preferably wound around condenser 32. Coil 34 offers little or no D.C. resistance to the ignition system and acts as a shock absorber to block surges of current from coil 17 to contacts 12. The surges are directed to ground at 40 by condenser 32.

The device as illustrated, permits the normal flow of DC. current therethrough to saturate coil 30. In most cases however, after contacts 12 have opened and a spark has been produced, a high voltage is induced in the primary 17 of coil 16 which flows back through contacts 12 as they close causing burning and oxidation of the points. Excessive peak voltages are reduced by the combination of condenser 32 and coil 30 thereby prolonging the life of contacts 12 as well as providing extra energy for cold weather starting.

The entire device is adapted for easy installation in an automobile and is preferably encapsulated in a plastic or ceramic case. The electrical characteristics of the condenser 32 and the choke coil 30 may be varied to suit different applications. A typical unit may be cased in a housing about the siz of an adult thumb having a ground connection at the bottom and a wire lead for connection with the breaker points extending from the top. A third connection at the top is provided connection to a lead from the primary side of the ignition coil.

Thus I have set forth the details of a new and improved ignition accessory designed to prevent the break down of ignition points resulting from excessive voltages and to provide extra capacity in low temperatures. The device is characterized by a high degree of capability, yet it is inherently rugged in construction, requiring no electron tubes, complex mechanical parts or other features that Would tend to cause malfunctioning or Wear.

Although I have described my invention in particular terms, it is understood that I am not limited thereby, but limit my invention by thescope of the appended claims.

I claim:

1. In a spark ignition system a spark coil having primary and secondary windings, an output circuit for said spark coil including said secondary Winding, a primary circuit for said spark coil including said primary winding, a grounded circuit breaker, a grounded condenser connected to said circuit breaker at a locality above ground and shunting the same and a grounded battery connected to one end of said primary Winding, the combination of a choke connected to one end of said circuit breaker and condenser at a point above ground and at its other end to the other end of said primary winding, and a grounded condenser connected to said choke and to said primary Winding at the last referred to ends thereof.

2. In a spark ignition system, a spark coil having primary and secondary windings, an output circuit for said spark coil including said secondary winding, a primary circuit for said spark coil including said primary winding, a battery connected at one terminal to one end of said primary winding, a circuit breaker connected at one terminal to the other terminal of said battery and a first condenser shunting said circuit breaker, the combination of a choke connected to the other terminal of said circuit breaker and to the other end of said primary winding and a second condenser connected to the last referred to terminal of said battery and to the last referred to end of said choke.

3. In a spark ignition system, a spark coil having primary and secondary windings, an output circuit for said spark coil including said secondary Winding, a primary circuit for said spark coil including said primary winding, a grounded circuit breaker, a grounded condenser connected to said circuit breaker at a locality above ground and shunting the same and a grounded battery connected to one end of said primary winding, the combination of a unit comprising a condenser and a low impedance choke consisting of a coil of wire wound about the condenser and having one end connected to one terminal of the condenser and to said primary winding, the other end of said choke being connected to the circuit breaker at its terminal above ground and the other end of said condenser being connected to ground.

References Cited in the file of this patent UNITED STATES PATENTS 2,389,639 Williams Nov. 27, 1945 2,440,154 Oles Apr. 20, 1948 2,443,060 Wall June 8, 1948 2,819,428 Bowlus et a1. Jan. 7, 1958 

